1. Field of the Invention:
The present invention relates to a magnetic recording and reproducing device, and particularly to a helical scan type magnetic recording and reproducing device capable of still and slow motion reproduction.
2. Description of the Prior Art:
In a video tape recorder (VTR) for recording and reproducing an image on and from a magnetic tape helically wound on a rotation head, an azimuth recording system in adopted in order to make high density recording possible. By means of a pair of rotation heads with different inclination angles, an azimuth track is formed on the tape in order to eliminate the cross stroke interference due to tracing the adjacent track, and to realize a high density recording in a narrow recording track.
Further, an azimuth recording type helical VTR arranged so that in addition to the principal rotation head for image reproduction, a double azimuth head is provided on the rotation head, has been proposed. In case of such a two-head-type helical VTR, the principal rotation head is used for ordinary reproduction, while the double azimuth head is used for still or slow motion reproduction. FIG. 1 shows the outline of the arrangement of the rotation heads of such a device. As is shown in the drawing, the rotation head Ha is the one having the plus azimuth, Hb is the one having the minus azimuth, and an auxiliary head having a plus azimuth and carrying out the still and the slow motion reproduction is provided at the side of the head Hb. Accordingly, in case of the ordinary image reproduction, the plus azimuth head Ha and the minus azimuth head Hb trace the azimuth recording adjacent track on the tape to pick up the image signal. Further, in case of still reproduction, the auxiliary plus azimuth head at the side of head Hb traces the same track that the plus azimuth head Ha has traced so as to reproduce the still image signal from the tape of 1 track, 1 field recording. Thus, a clear still image even of a scene with quick motion can be reproduced. In case of the above-mentioned conventional device, the auxiliary heads are used only for still and slow motion reproduction, so that the utilization of the auxiliary heads is low and therefore the cost of the device is high, which is not economical.
It is a recent trend that in order to realize high density recording and reproducing on and from a magnetic recording medium, the track pitch is narrowed, so that a more correct tracking system in which magnetic heads trace the track must be developed. For this purpose, an automatic scan tracking device making use of a bimorph plate consisting of piezo elements as the head support arm, is under consideration. For example, U.S. Pat. No. 4,203,140 discloses a device arranged so that one or more auxiliary heads are provided in the head construction in such a manner that automatic tracking is carried out with the displacement of the piezo element due to the outputs of the heads. The auxiliary heads used for such a device are used for reproduction of a control pilot signal or for the detection of the envelope of the image signal, and not for the reproduction of the image signal.